A device such as this is designed to reduce the stresses applied to the occupant of the vehicle sitting on the seat by progressively absorbing the kinetic energy to which his body is subjected. The invention is more particularly intended to absorb energy in the event of a rear impact, but can also be applied to a frontal impact or even to other types of impact.
Documents DE-196 13 506 and DE-198 07 581 each describe an energy absorbing device of the aforementioned type comprising a first element substantially in the form of a (shaped) plate that has a hole and a second element inserted in the hole, said first element comprising a succession of cutouts that succeed one another in a direction of deformation and between them define a succession of bridges (strips) extending in a direction of elongation transverse to the direction of deformation, said cutouts each having a length in the direction of elongation.